A Small Broadband Spectral Detector Design

Software Radio is a brand new architecture. As the technology develops,Software Radio gets much wide application. Its principle is to place the ADconverter much close to the antenna and construct a general open platform fordifferent wireless communication system. It takes a model of 'AD-DSP-DA'. Manyfunctions in wireless communication can be accomplished owing to the flexibility ofsoftware reprogramming such as frequency band select, modulation anddemodulation, different communication format, communication protocol. As to thelimitation of the hardware speed, Software Radio cannot be fully applied to thedigitalization of RF signal. What we apply in engineering practice is that RF frontend be designed with analog component and digitalized in the intermediatefrequency band.What we developed here is a small wide-band signal spectrum detector. Itsdesign compromises the advanced Software Radio architecture with our engineeringtechnology level. The system architecture is superheterodyne-frequency downconverter plus intermediate frequency band digitalization. An ARM processor isused for data processing and system control. Software is programmed to detect andclassify in the signal frequency domain. FFT is the main measurement for the timedomain to frequency domain transform. Different method is used to detect andanalyze the spectrum of different communication signal such as BPSK and DSSSunder low SNR. The whole system is multifunctional in a small size and meaningfulin engineering application.